Possible explanations for the common clinical familial hypercholesterolemia phenotypes in the Faroe Islands.

BACKGROUND: The prevalence of clinical familial hypercholesterolemia (FH) is very high in the Faroe Islands, but the possible causes are unknown. OBJECTIVES: We aimed to describe potential genetic causes of FH in the Faroe Islands and to investigate whether levels of lipoprotein(a) and measures of dietary habits were associated with clinical FH in the Faroe Islands. METHODS: In this case-control study, we identified potential clinical FH cases aged 18-75 years registered within a nationwide clinical laboratory database in the Faroe Islands and invited them for diagnostic evaluation according to clinical FH scoring systems. Controls were identified in the background population. Lipoprotein(a) was measured in plasma, while the fatty acid composition was determined in adipose tissue. The habitual diet of the participants was assessed using a food frequency questionnaire. Genetic testing for FH and polygenic variants was performed in a selection of clinical FH cases. RESULTS: A total of 121 clinical FH cases and 123 age- and sex-matched controls were recruited. We found a very low frequency of monogenic FH (2.5%), but a high level of polygenic FH (63%) in those genetically tested (67%). High levels of plasma lipoprotein(a) were associated with high odds of clinical FH. Clinical FH cases had a lower intake of saturated fatty acids (SFAs) measured by a high fat-score and a lower content of SFAs in adipose tissue compared with controls. CONCLUSION: The high prevalence of FH in the Faroe Islands may be due to polygenic causes of hypercholesterolemia and to a lesser extent other genetic factors and elevated plasma lipoprotein(a) levels.

Subclinical atherosclerosis determined by coronary artery calcium deposition in patients with clinical familial hypercholesterolemia.

Background and aims: Limited knowledge exists regarding the association between coronary artery calcium (CAC) deposition in patients with clinical familial hypercholesterolemia (FH) and FH subtypes such as polygenic causes. We studied CAC score in patients with clinical FH and subtypes including polygenic causes of FH compared to healthy controls. Methods: In a case-control study, we identified potential clinical FH cases registered with an LDL-C >6.7 mmol/l within a nationwide clinical laboratory database on the Faroe Islands and invited them for diagnostic evaluation according to clinical FH scoring systems. Controls were identified in the background population. All subjects were aged 18-75 years and without a history of cardiovascular disease. FH mutation testing and genotypes of twelve LDL-C associated single nucleotide polymorphisms were determined using conventional methods in selected individuals. CAC scores were assessed by cardiac CT. Odds ratios obtained using multivariate logistic regression were used as measures of association. Results: A total of 120 clinical FH patients and 117 age- and sex-matched controls were recruited. We found a very low frequency of monogenic FH (3%), but a high level of polygenic FH (60%) in those genetically tested (54%). There was a statistically significant association between the CAC score and a diagnosis of clinical FH with the highest observed odds ratio of 5.59 (95% CI 1.65; 18.94, p = 0.006) in those with a CAC score ≥300 compared to those with a CAC of zero. In supplemental analyses, there was a strong association between CAC scores and clinical FH of a polygenic cause. Conclusion: We found a statistically significant association between CAC levels and clinical FH with the highest observed risk estimates among clinical FH cases of a presumed polygenic cause.

First reported case of Doyne honeycomb retinal dystrophy (Malattia Leventinese/autosomal dominant drusen) in Scandinavia.

BACKGROUND: Doyne honeycomb retinal dystrophy (DHRD)/malattia leventinese (ML) is an autosomal dominant, progressive retinal disorder characterized by massive central retinal drusen often partly coalescent forming a characteristic honeycomb-like pattern. Debut of vision loss often occurs in early to mid-adulthood, and the degree varies. A single variant in EFEMP1: c.1033C>T (R345W) has been identified as the cause in all cases. METHODS: Following DNA isolation, exome sequencing was performed in seven genes associated with flecked retina. Direct sequencing was used for variant verification. RESULTS: We report the first Scandinavian case of molecular genetically verified DHRD/ML: a 57-year-old woman debuting with vision loss and metamorphopsia. On both eyes, ophthalmological findings included massive hard drusen in the macular region and nasal to the optic disc as well as macular hyperpigmentation. Secondary choroidal neovascularizations were identified on both eyes, and anti-vascular endothelial growth factor was administered, without effect. CONCLUSION: Molecular genetic investigation revealed heterozygosity for the known pathogenic missense variant in EFEMP1: c.1033C>T (R345W) previously reported in relation to DHRD/ML. Family history revealed no other cases of similar visual impairment suggesting a de novo mutation. Furthermore, there was no correlation between the unique DHRD/ML haplotypes reported in the literature and our patient.

First reported CABP2-related non-syndromic hearing loss in Northern Europe.

BACKGROUND: CABP2-related non-syndromic hearing loss have only been reported in a few families worldwide (Iran, Turkey, Pakistan and Italy). The hearing loss was in these cases described as prelingual, symmetrical, and moderate to severe. METHODS: Following DNA isolation, exome sequencing was performed in 123 genes related to non-syndromic hearing loss. Variant verification and carrier testing were performed by direct sequencing. RESULTS: We report the first Northern European individual with CABP2-related hearing loss: an 8-year-old Danish Caucasian boy with non-syndromic, prelingual, and sensorineural hearing loss, who is homozygous for the splice site variant CABP2: c. 637+1G>T previously found in three Iranian families and in one Pakistani family. Both parents are of Danish Caucasian origin with no known history of consanguinity. This is in contrast to the four reported Middle Eastern families, who all were consanguineous. However, loss of heterozygosity in a 3.2 Mb area on chromosome 11 including CABP2 was observed, suggesting a common parental ancestor. CONCLUSION: We report the first case of CABP2-related autosomal recessive hearing loss in Northern Europe. The index is of Danish Caucasian origin and found to be homozygous for the splice site variant c.637+1G>T.

Detection of PMS2 Mutations by Screening Hereditary Nonpolyposis Colon Cancer Families from Denmark and Sweden.

Background and Aims: Hereditary nonpolyposis colon cancer (HNPCC) and Lynch syndrome (LS) are characterized by defects in the mismatch repair (MMR) system, which protects the integrity of the genome. Pathogenic variants in four MMR genes (MLH1, MSH2, MSH6, and PMS2) are responsible for LS, an autosomal, dominant hereditary disease that occurs with a frequency of 2-5% among all colorectal cancer cases. It has been estimated that ∼2-5% of all pathogenic variants found in the four MMR genes in LS cases are detected in the PMS2 gene. An overview of detected variants is presented here. Materials and Methods: Long-range (LR) PMS2 polymerase chain reaction (PCR) and PMS2 multiplex ligation probe amplification (MLPA) assays were used to detect PMS2 variants in ∼1500 probands. In a subset of the probands, pathogenic PMS2 variants were detected by next-generation sequencing, and all detected variants were confirmed by LR-PCR combined with an MLPA assay. Results: A summary of PMS2 mutation analyses performed on colon cancer patients from molecular diagnostic laboratories in Denmark and Sweden is presented. By screening ∼1500 HNPCC probands, a total of 40 different PMS2 variants were detected in 71 probands (5%); 20 variants were classified as pathogenic (C5), 2 variants as likely pathogenic (C4), 15 variants as variants of unknown significance (VUSs) (C3), 1 variant as likely benign (C2), and 2 variants as benign (C1). In total, 22/71 (31%) of the probands carried a pathogenic sequence variant. Among the probands with isolated loss of pPMS2 expression, the fraction of pathogenic variants was 20/35 (55%). Conclusions: Approximately 5% of the probands found in the Danish and Swedish populations presented here carried a PMS2 variant. In this study, six novel pathogenic variants and seven VUSs are reported.

First reported adult patient with TARP syndrome: A case report.

TARP syndrome (talipes equinovarus, atrial septal defect, Robin sequence, and persistence of the left superior vena cava) is a rare X-linked syndrome often resulting in pre- or post-natal lethality in affected males. In 2010, RBM10 was identified as the disease-causing gene, and we describe the first adult patient with TARP syndrome at age 28 years, hereby expanding the phenotypic spectrum. Our patient had Robin sequence, atrial septal defect, intellectual disability, scoliosis, and other findings previously associated with TARP syndrome. In addition, he had a prominent nose and nasal bridge, esotropia, displacement of lacrimal points in the cranial direction, small teeth, and chin dimple, which are the findings that have not previously been associated with TARP syndrome. Our patient was found to carry a hemizygous c.273_283delinsA RBM10 mutation in exon 4, an exon skipped in three of five protein-coding transcripts, suggesting a possible explanation for our patient surviving to adulthood. Direct sequencing of maternal DNA indicated possible mosaicism, which was confirmed by massive parallel sequencing. One of two sisters were heterozygous for the mutation. Therefore, we recommend sisters of patients with TARP syndrome be carrier tested before family planning regardless of carrier testing results of the mother. Based on our patient and previously reported patients, we suggest TARP syndrome be considered as a possible diagnosis in males with severe or profound intellectual disability combined with septal heart defect, and Robin sequence, micrognathia, or cleft palate.

The transcript elongation factor SPT4/SPT5 is involved in auxin-related gene expression in Arabidopsis.

The heterodimeric complex SPT4/SPT5 is a transcript elongation factor (TEF) that directly interacts with RNA polymerase II (RNAPII) to regulate messenger RNA synthesis in the chromatin context. We provide biochemical evidence that in Arabidopsis, SPT4 occurs in a complex with SPT5, demonstrating that the SPT4/SPT5 complex is conserved in plants. Each subunit is encoded by two genes SPT4-1/2 and SPT5-1/2. A mutant affected in the tissue-specifically expressed SPT5-1 is viable, whereas inactivation of the generally expressed SPT5-2 is homozygous lethal. RNAi-mediated downregulation of SPT4 decreases cell proliferation and causes growth reduction and developmental defects. These plants display especially auxin signalling phenotypes. Consistently, auxin-related genes, most strikingly AUX/IAA genes, are downregulated in SPT4-RNAi plants that exhibit an enhanced auxin response. In Arabidopsis nuclei, SPT5 clearly localizes to the transcriptionally active euchromatin, and essentially co-localizes with transcribing RNAPII. Typical for TEFs, SPT5 is found over the entire transcription unit of RNAPII-transcribed genes. In SPT4-RNAi plants, elevated levels of RNAPII and SPT5 are detected within transcribed regions (including those of downregulated genes), indicating transcript elongation defects in these plants. Therefore, SPT4/SPT5 acts as a TEF in Arabidopsis, regulating transcription during the elongation stage with particular impact on the expression of certain auxin-related genes.

Identification of triclosan-degrading bacteria using stable isotope probing, fluorescence in situ hybridization and microautoradiography.

Triclosan is considered a ubiquitous pollutant and can be detected in a wide range of environmental samples. Triclosan removal by wastewater treatment plants has been largely attributed to biodegradation processes; however, very little is known about the micro-organisms involved. In this study, DNA-based stable isotope probing (DNA-SIP) combined with microautoradiography-fluorescence in situ hybridization (MAR-FISH) was applied to identify active triclosan degraders in an enrichment culture inoculated with activated sludge. Clone library sequences of 16S rRNA genes derived from the heavy DNA fractions of enrichment culture incubated with (13)C-labelled triclosan showed a predominant enrichment of a single bacterial clade most closely related to the betaproteobacterial genus Methylobacillus. To verify that members of the genus Methylobacillus were actively utilizing triclosan, a specific probe targeting the Methylobacillus group was designed and applied to the enrichment culture incubated with (14)C-labelled triclosan for MAR-FISH. The MAR-FISH results confirmed a positive uptake of carbon from (14)C-labelled triclosan by the Methylobacillus. The high representation of Methylobacillus in the (13)C-labelled DNA clone library and its observed utilization of (14)C-labelled triclosan by MAR-FISH reveal that these micro-organisms are the primary consumers of triclosan in the enrichment culture. The results from this study show that the combination of SIP and MAR-FISH can shed light on the networks of uncultured micro-organisms involved in degradation of organic micro-pollutants.

Biodegradation of triclosan and formation of methyl-triclosan in activated sludge under aerobic conditions.

Triclosan is an antimicrobial agent which is widely used in household and personal care products. Widespread use of this compound has led to the elevated concentrations of triclosan in wastewater, wastewater treatment plants (WWTPs) and receiving waters. Removal of triclosan and formation of triclosan-methyl was investigated in activated sludge from a standard activated sludge WWTP equipped with enhanced biological phosphorus removal. The removal was found to occur mainly under aerobic conditions while under anoxic (nitrate reducing) and anaerobic conditions rather low removal rates were determined. In a laboratory-scale activated sludge reactor 75% of the triclosan was removed under aerobic conditions within 150 h, while no removal was observed under anaerobic or anoxic conditions. One percent of the triclosan was converted to triclosan-methyl under aerobic conditions, less under anoxic (nitrate reducing) and none under anaerobic conditions.

The transcript elongation factor FACT affects Arabidopsis vegetative and reproductive development and genetically interacts with HUB1/2.

The facilitates chromatin transcription (FACT) complex, consisting of the SSRP1 and SPT16 proteins, is a histone chaperone that assists the progression of transcribing RNA polymerase on chromatin templates by destabilizing nucleosomes. Here, we examined plants that harbour mutations in the genes encoding the subunits of Arabidopsis FACT. These experiments revealed that (i) SSRP1 is critical for plant viability, and (ii) plants with reduced amounts of SSRP1 and SPT16 display various defects in vegetative and reproductive development. Thus, mutant plants display an increased number of leaves and inflorescences, show early bolting, have abnormal flower and leaf architecture, and their seed production is severely affected. The early flowering of the mutant plants is associated with reduced expression of the floral repressor FLC in ssrp1 and spt16 plants. Compared to control plants, reduced amounts of FACT in mutant plants are detected at the FLC locus as well as at the locations of housekeeping genes (whose expression is not affected in the mutants), suggesting that expression of FLC is particularly sensitive to reduced FACT activity. Analysis of double mutants that are affected in the expression of both FACT subunits and factors catalysing the mono-ubiquitination of histone H2B (HUB1/2) demonstrates that they genetically interact to regulate various developmental processes (i.e. branching, leaf venation pattern, silique development) but independently regulate the growth of leaves and the induction of flowering.